Opening Britain's postal system to private competition could leave some homes without a delivery service, MPs have warned.

Under new rules, private firms will compete on equal terms with the Royal Mail from January 1.

If they are particularly successful, the Royal Mail may not be able to afford a universal service, the Commons trade and industry committee said.

Postcomm, the industry regulator, said it believed the market was ready.

The Royal Mail is legally required to provide a "universal service" but MPs said they were concerned over how that would be defined.

The committee is really anxious to protect a universal service similar to the one we have at present

Peter LuffCommittee chairman

"We emphasise that a universal service is not worthy of the name if it allows for any geographic exemptions," the report said.

It added: "The regulator must remain vigilant to ensure that greater competition in the postal services market does not come at the cost of the universal service."

Service threat

Tory committee chairman Peter Luff said: "If competition is more intense than people are expecting that service could be threatened in all kinds of ways, particularly as private sector operators cream off more profitable parts of the market."

A "safety net" fund requiring private competitors to help pay for Royal Mail deliveries would "almost inevitably come too late", the MPs further warned.

Mr Luff said: "The government, regulator and the Royal Mail will have to move quickly if the universal service is in jeopardy.

"The committee is really anxious to protect a universal service similar to the one we have at present."